Moving to Berlin-Flat hunting!

Hello I am in the beginning of moving to Berlin (Need to be all moved into a flat by November 7th) The issue is the rules seem quite strange as a bank needs information that one can not have unless they are already living in Berlin?

Can anyone take some time and shine some insight on this for me?

Also if anyone knows of any 55m2 apartments that are looking for new tenants please let me know